Plastic insulation and method of manufacture



Patented Feb. 8, 1949 PLASTIC INSULATION AND METHOD OF MANUFACTURE Manuel R. Ximenez, Fanwood, John H. Ferguson,

Somerville and Stanley 0. Bunce, Plainfield, N. J., assignors to Johns-Manville Corporation,

New York, N. Y.. a corporation of New York No Drawing. Application August 17, 1945,

A Serial No. 611,250

10 Claims. (Cl. 260-173) This invention relates to plastic insulation and the method of making the same. The present plastic insulation is intended primarily for use as a thermal insulation covering for valves and other irregular surfaces in refrigeration or low temperature systems.

The insulation herein described has been developed to meet a substantial demand for a plastic insulating material which can be easily and safely employed for covering metallic objects of irregular shape such as valves, elbows and other surfaces which. because of their shape, cannot be readily covered by the usual prefabricated insulation blocks or tubular pipe insulation shapes. Plastic insulating compositions at present available generally lack one or more desirable properties for the stated purpose. Many such compositions develop brittleness on setting up or aging and lack permanent adhesiveness for metal surfaces. Compositions containing water are unsuitable on refrigerated surfaces, and serious risks are involved in handling compositions containing toxic or inflammable solvents. Some conventional plastic insulating compositions require mixing at the time of application or are difficult to apply because of excessive tackiness such as to stick to the hands or tools of the user. Many such compositions lack cohesive strength at the time of application and thus require mechanical support while setting up. Some compositions lack cohesiveness even after setting up and require permanent mechanical support. Compositions which contain moisture or solvents when applied undergo shrinkage in volumeafter application and require considerable time for drying or setting up before application of a final protective covering or finishing coat. Few available compositions possess the inherent low density and high proportion of voids which are desirable for good heat and cold insulation.

A primary object of the present invention is to provide a plastic heat insulating composition which exhibits none of the aforementioned defects and which has good insulating properties and ficient method of making plasticinsulation compositions having the properties above outlined.

With the aforementioned objects in view, the invention consists in the improved plastic insulating composition and method of making the same which are hereinafter described and particularly defined by the accompanying claims.

The plastic insulation which forms the subject of the present invention contains no volatile solvents. It requires no mixing or addition of components at the time of application to a surface to be covered thereby, and is supplied in a form ready to apply simply by pressing in place and shaping manually or by the tools of the user. After once being applied and shaped it quickly develops a fairly strong insulation covering which is permanently cohesive. resilient and adhesive. By suitable selection of ingredients the composition can be rendered fireproof.

The present plastic insulating composition is made up by coating a particulate granular or fibrous filler material of good insulating characteristics with a liquid elastomer,. and by subsequently heating the elastomer coated particles to polymerize the elastomer to an intermediate reaction stage in which it is not obiectionably tacky to the hands. At this stage the elastomer possesses resilience and high cohesive properties when separate portions of the insulating composition are manually pressed together and shaped. The pressure sensitive elastomer which imparts the aforementioned desirable characteristics to the insulating composition, consists essentially of a heat hardenable, intermediate reaction product formed by coupling a preactivated drying oil or semi-drying oil with an oil soluble phenolic resin formed by condensation reaction of an aldehyde and a p-tertiary alkyl phenol the alkyl radical of which may contain 4 to-10 carbon atoms.

During the coating operation some of the liquid elastomer enters surface pores or fissures of the cork granules or other granular or fibrous insulating fillers by absorption and penetration. 0n subsequent heat polymerization of the coated filler material a strong unitary bond-is developed between each' filler particle and its viscous pressure sensitive coating. The composition-exhibits sufficient pressure sensitivity so that it can be manually compressed and shaped at normal temperature to form a strongly and permanently cohering mass of the coated particles which is permanently adherent to the surface to be coated.

granular expanded vermiculite. An example of a plastic composition adapted for insulating heated surfaces is one prepared by coating fibrous mineral wool with 15-25% by weight of the clastomer in liquid state, and thereafter heating the coated fibers to polymerize and set the elastomer to a strongly adhesive and cohesive, slightly tacky state.

Suitable compositions for insulating cold. irregular metal surfaces such as refrigeration pipe fittings are the following: 30-60% by weight of cork granules, preferably graded as to size over the range 8-30 mesh; 40-70% by weight of a liquid reaction product of pre-activated linseed oil and a p-tertiary alkyl phenol-formaldehyde resin; and -10% by weight of the composition of a flameprooflng plasticizer, specifically tricresyl phosphate.

A specific formula for making the liquid elastomer is as follows:

. Parts by weight Pre-activated linseed oil 2.5-3 Oil soluble phenolic resin 2.5-2

The pre-activated linseed oil is prepared by heating raw linseed oil in the presence of about 5% of anhydrous zinc chloride for about 20 minutes at a temperature of approximately 200 C. The thus heat reacted oil is cooled and separated from solid residue, as by decantation. The composition and molecular structure of the oil is thus changed so that it .is rendered reactive with the oil-soluble phenol-formaldehyde resin at a comparatively low temperature.

The oil soluble resin may be. employed in dry, finely divided solid form comprising an intermediate product of reaction under alkaline conditions between formaldehyde or other reactive methylene compound and p-tertiary alkyl phenol in which the alkyl radical contains between 4 and carbon atoms in its molecule. A suitable oilsoluble resin is a heat-reactive p-tertiary butyl phenol-formaldehyde resin which is available under the name Amberol ST-18'7. Another suitable resin is heat-reactive p-tertiary amyl phenolformaldehyde.

In producing the liquid elastomer finely divided solidoil soluble resin may be melted and dissolved in the pre-activated linseed oil by adding the resin to the oil in a container such as a varnish kettle while the oil is heated to a temperature inthe neighborhood of 90-130 C. The oil and resin mixture is stirred and maintained at the indicated temperature for a period of about 40 minutes to 1 hour, by the end of which time an initial coupling or condensation reaction has taken place between the activated oil and the resin.

It is preferred'to use an oil-soluble resin in liquid state because the liquid resin may be mixed with the activated linseed oil at room temperature, and the mixture thus formed may be used immediately for coating the cork or other insulating filler material, before subjecting the resulting composition to heat treatment to convert the elastomer coating to an intermediate reaction stage having adhesive and cohesive characteristics suitable for the binder component of the insulating composition.

The term liquid elastomer" has been employed herein to describe the homogeneous liquid mixtures of activated drying oil and oil-soluble resin i eas which result when the resin in finely divided about 0. However, some reaction may occur, and when the liquid mixture is heated to temperatures in the range -l50 C. a true coupling reaction takes place between the oil and the resin, as evidenced by evolution of heat of reaction attended by some frothing and some evolution of water vapor.

Inmaking up the plastic insulating composition the elastomer is applied to the granular cork or other insulating filler while in a liquid state, in order that the elastomer and filler may be more readily mixed, and in order that each granular filler particle may be completely coated with the elastomer material. In producing the plastic insulating composition, the granular or fibrous insulating filler may be weighed into a paddle type mixer of the horizontal shaft type, and the liquid elastomer added thereto. The mass is agitated in the mixer until the cork or other insulating filler material is uniformly coated with the liquid elastomer. The thus coated cork granules may be agitated at a temperature of about -130" C. for a period of one to two hours to polymerize the elastomer to a. pressure sensitive, slightly tacky condition.

The heat treatment may alternatively be carried out by spreading the coated granules over a supporting surface and baking them in a heated chamber at a rate slow enough to promote slow hardening reaction at the indicated temperature. In a suitably heat cured condition the dry plastic insulation can be picked up by hand or by mechanical means and transferred in a loose or uncompacted state into sealed metal containers. When the plastic insulation thus produced is charged to sealed containers while it retains slight tackiness, it has an apparent density of about 1.4 lbs. per gallon. It has elasticity and cohesive properties resembling those of unvulcanized rubber, and can be removed from the container and readily pulled apart for manual application to unheated irregular surfaces such as pipe fittings.

At the time of application to a surface to be insulated, the dry plastic insulation has suiiicient tack and adhesive characteristics to adapt it for manual application. These properties are preserved over a period of several months storage in sealed containers, without the presence of any volatile solvent in the composition. Since the plastic insulation at the time of its removal from the container retains its original pressure sensitivity and slight tackiness resembling that of 1mvulcanized rubber, it also retains a high degree of cohesiveness and adhesiveness for metal, and may therefore be applied without the use of an adhesive primer cement coating. However, because of the high proportion of insulating filler material such as cork which is present in the composition, more satisfactorily strong adherence to a metal surface is secured when a primer coat of cement made from the elastomer binder component of the plastic insulation is first applied and dried to a tacky coating over the metal surface, before applying the plastic insulation cover.

Dry plastic insulation made as herein described by heat curing elastomer. coated cork granules, may be readily shaped and molded manually to a final density of 10-25 lbs. per cubic it. For example, an insulating composition containing 40% cork and about 60% binder can be molded to a final density of about 15 lbs. per cubic ft. and to a final form having substantially smooth surfaces. Layers of insulation thus applied to irregular pipe fittings retain considerable permanent cohesive strength and soul! resistance, and permanent adhesion to the metal surface to which the insulation is applied. The composition after application retains sui'licient strength and resilience so that it is not disturbed or dislodged while being wrapped with a covering fabric tape under comparatively high tensile pull. Insulation coverings up to 2-3 inches in thickness can be manually applied to valves or other irregular metal surfaces andused in unsupported condition at temperatures not exceeding 100 F. Insulation layers of much greater thickness can be similarly applied when they are retained and supported by fabric tape wrapping.

The elastomer binder which results from either heat or air hardening of the plastic insulation is an iniusible, insoluble adhesive film oi exceptional bonding strength, flexibility and resilience.

- Since the liquid elastomer is not diluted with volatile solvents or other liquids at the time of its application to the surfaces of cork or other insulating fillers, its bonding strength and adhesiveness is not adversely affected by the necessity of effecting removal of such volatile constituents prior to the final hardening treatment. The result is that the final hardened films of the binder are of uniform thickness and adhesiveness throughout the bonding area, without the presence of blisters, cracks and weak spots of a type which normally result when a solvent is liberated during the drying out of a film containing the same.

As stored in sealed cans and as removed from the cans immediately prior to application, the

The cured insulationcovering is flexible and waterproof and is substantially inert to dilute acids and alkalis.

Since many variations may be made from the illustrative details given, without departing from the scope of the invention, it is intended that theinvention should be limited only by the terms of the claims interpreted as broadly as consistent with novelty over the prior art.

What we claim is: I

1. A plastic insulating composition comprising heat insulating particles individually coated with a pressure sensitive, slightly tacky condensation product of zinc chloride heat treated drying oil and oil-soluble p-tertiary alkyl phenol-formaldehyde resin with 4-10 carbon atoms in the alkyl group. said' composition being free of volatile solvents and being moldable by manual pressure at normal temperature to form a permanently cohesive and adhesive insulation mass.

2. A plastic insulation composition comprising 30-60% by weight of finely 'divided insulating filler material, the individual particles of which are coated with a pressure sensitive, slightly tacky elastomer polymer of a condensation product of a zinc chloride heat treated drying oil and an oil-soluble p-tertiary alkyl phenolformaldehyde resin with 4-5 carbon atoms in the alkyl group, said composition having a density not substantially exceeding 25' lbs. per cubic ft. and being compressible manually at normal temperature to form a strong cohesive insulating mass.

3. A plastic insulating composition comprising finely divided insulating filler material individual particles oi which are coated with a pressure sensitive, slightly tacky heat hardenable elastomer, said elastomer comprising the reaction product of about 3 parts by weight of zinc chloride heat treated drying oil and 2 parts by weight of oil-soluble p-tertiary alkyl phenolformaldehyde resin with 4-5 carbon atoms in the alkyl group, and said elastomer containing 5-10% by weight of tricresyl phosphate as a homogeneous mixture of finely divided cork particles and a binder therefor consisting of a heat hardenable reaction product of zinc chlo-- ride heat treated linseed oil and an oil-soluble phenol-formaldehyde resin comprising p-tertiary alkyl phenol in which the alkyl radical contains 4-10 carbon atoms.

6. A plastic insulating composition comprising 30-60% by weight of cork granules graded as to size between 8 and 30'mesh, and a coating for the individual granules comprising pressure sensitive, slightly tacky condensate polymer of zinc chloride heat treated linseed oil and an oilsoluble p-tertiary alkyl phenol formaldehyde resin with 4-5 carbon atoms in the alkyl group, said composition having a loose granular form which is manually moldable at normal temperature to produce a cohesive covering of not to exceed 25 lbs. per cubic it. density.

7. The method of producing a plastic insulatingcomposition which comprises, intimately mixing a finely divided insulating filler material with a heat polymerizable liquid binder comprising a mixture of zinc chloride heat treated drying oil and p-tertiary alkyl phenol-formaldehyde resin with 4-10 carbon atoms in the alkyl group to coat individual particles of the filler material with the binder, and spreading out the coated particles and heating them to convert the binder to apressure sensitive, slightly tack elastomer condition. 8. The method 01 manufacturing a low density insulating putty which comprises, admixing finely divided cork with a liquid binder comprising the heat hardenable reaction product of an oil-soluble p-tertiary alkyl phenol-formaldehyde resin with 4-10 carbon atoms in the alkyl group and zinc chloride heat treated linseed oil, and.

the binder to a pressure sensitive, slightly tacky condition.

10. The method of manufacturing aplastic insulating composition which is manually moldable at normal temperature comprising, intimately mixing 30-60% by weight oi. cork granules graded as to size largely between 8 and 30 mesh with a heat polymerizable liquid elastomer comprising a zinc chloride heat treated linseed oil-p-tertiary amyl phenol-formaldehyde resin condensate, said elastomer containing a small amount of a tri-aryl phosphate flameproofing agent, agitating the mixture to coat the individual cork granules with the elastomer, and spreading out the thus coated'mass of granules and subjecting said mass to heating at a temperature of about 105 C. for several hours to polymerize the liquid elastomer to a pressure sensitive, slightly tacky cohesive and adhesive state.

MANUEL R. IHMENEZ. JOHN H. FERGUSON. STANLEY C. BUNCE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

